Many conventional imaging devices such as cameras, camcorders, and other alternatives, use automatic focusing systems to capture sharper images easily. Conventional automatic focusing lens systems comprise a series of lenses, lens moving mechanisms, image sensors and signal processors. When the imaging device and/or the imaged object is moved abruptly, the imaging device loses focus of an image because conventional automatic focusing systems have low focusing speeds. Therefore, the imaging device obtains a blurred image.
Most conventional automatic focusing imaging devices use an electromagnetically driven motor and/or piezo-electrically actuated apparatus to move one or more lenses for focusing. But the response speed of conventional automatic focusing systems is too slow because the conventional refracting lenses and conventional lens-moving mechanisms incorporated in the imaging device have considerable inertia. For the electromagnetic motor, the response speed is limited by the magnetic inductance. Imaging devices with fast automatic focusing have not appeared yet.
Thus there is a practical need for an improved automatic focusing system that enables clear images to be captured within an instance of time. Such system must be easy to manufacture and adapted for use with existing imaging devices.